The goal of this proposal is to identify the genes that specify the pancreatic fates to isolate and characterize putative stem cells from the pancreas. We will use differential cloning techniques to isolate genes that are specifically expressed in an undifferentiated but committed pancreas rudiment. In situ hybridization will be used to verify temporal and spatial expression pattern of candidate genes. We will explore the use of retroviruses to introduce antisense RNA of candidate genes into pancreatic epithelium or ectopicaly express them in other cell types and test their effects. In addition, we will establish pancreatic ductile cell lines and study their stem cell capability to form pancreatic islet and acinar cells. These tests will be performed both in vivo and in vitro: the cell lines will be grown in organ culture system to test their capacity to form islet and acinar cells. Cell lines will also be implanted into the embryonic and postnatal pancreas and their ability to form islet and acinar cells be determined by immuno-staining.